1. Field of the Invention
The present invention relates to an apparatus for transferring objects in integrated circuit production. More particularly, the present invention relates to a robot blade for transferring substrates through a processing system while reducing the idle time of the process chamber and the number of strokes to effect substrate transfer.
1. Background of the Related Art
The advantages of using robots in the production of integrated circuits to transfer substrates throughout a processing system are well established. Current practice includes the use of robot arms to move substrates from a loading port into various process chambers within a multiple chamber processing system. Various robot arm designs, including frog-leg type and single-arm type, are currently employed in processing chambers. Typically a robot blade having a substrate supporting surface is attached to the end of the robot arm to hold the substrate while it is being transferred. The robot arm can retrieve a substrate from a particular processing chamber or a substrate transferring chamber and shuttle the substrate into another chamber for additional processing. When substrate processing is complete, the robot arm returns the substrate to the loading port and another substrate is moved into the system by the robot for processing. Typically, several substrates are handled in this manner during each process run, and several substrates are passed through the system during a single process cycle.
In multiple chamber process systems, it is desirable to increase the substrate throughput of the system by concurrently processing substrates in each of the chambers. A typical substrate handling sequence used in multiple chamber process systems includes removing a substrate from a process chamber, moving the substrate to the next processing chamber or storing the substrate in a selected location, and then moving a new substrate from a storage location into the processing chamber from which the first substrate was removed. In this sequence of robot movements, the robot arm itself goes through significant repetitive rotations, extensions and retractions to simply exchange substrates within a selected processing chamber.
To increase the efficiency of substrate handling, a robot arm having the ability to handle two substrates at the same time may be provided. For example, FIG. 1 shows one such robot 2 including two sets of carrier arms 4 having robot blades 6 attached which are located at opposed ends of a support which is rotated about a pivot 8. One substrate may be stored on the blade 6 of one arm while the blade 6 on the other arm is used to retrieve and place a second substrate. Once the processed substrate is retrieved from the processing chamber by one arm, the arms are then rotated 180xc2x0 and the stored substrate may be placed into the processing chamber. Such mechanism does not allow for the immediate replacement of a new substrate in a process chamber after a processed substrate is removed because the robot must rotate 180xc2x0 to place the substrate on the second arm in a position for loading into the location from which the first substrate was removed.
In an attempt to further increase throughput and decrease chamber idle time associated with substrate transfer, another robot configuration includes coaxially upper and lower robots which can operate independently to remove a first substrate from a processing chamber and to insert a fresh substrate into the same processing chamber. The upper robot operates independently of the lower robot to obtain improved throughput and increased substrate handling capacity of the robot assembly as compared to the opposed, single plane, dual blade robots. The upper robot is typically stacked above the lower robot and the two robots may be mounted concentrically to allow fast substrate transfer. Either robot can be either a single blade robot or dual blade robot.
However, in order to achieve independent operation of the two robots, the assemblies require at least four magnetic or mechanical linkages and the same number of drive motors to maneuver the robot blades within the x-y plane. Compared to a conventional robot assembly, this dual robot configuration is considerably more complex, more expensive to build and maintain, and requires more space, typically above and below the transfer chamber. Moreover, this dual robot configuration still requires full-length strokes of insertion and retraction by each set of the robot arms, requiring the same number of robot movements.
In another attempt to increase throughput and decrease chamber idle time associated with substrate transfer, another robot configuration provides for linked, coordinated movement of simultaneous retraction of one blade and extension of another blade. As compared to a typical processing chamber which is idle during the period of time during which a first substrate is removed from the chamber and during which the robot assembly is rotated to insert a second substrate into the chamber, dual plane robots which can perform a shuttle operation offer a decreased amount of time in which the chamber is not operational. In addition, the time that the slit valve must remain open while the robot transfers a first substrate out of the chamber and inserts a second substrate into the chamber is also decreased. As a result, compared to conventional processing chambers, the throughput of the chamber can be increased and the period of time in which particles present outside the chamber may enter into the chamber can be decreased. However, this configuration still requires individual blades on different planes and multiple sets of robot arms to sequentially transfer a processed substrate out of a processing chamber and a fresh substrate into the processing chamber. Furthermore, this robot configuration still requires full-length strokes of insertion and retraction by each set of the robot arms.
There remains a need for a robot having minimal parts that reduces the amount of idle time that a chamber experiences during removal of a first substrate and insertion of a second substrate by reducing the number of robot movements and simultaneously reducing the amount of time that a slit valve needs to be opened during this sequence, resulting in higher throughput. There is also a need for a robot which minimizes the size of a slit valve opening while capable of transferring substrates on multi planes.
The present invention provides an apparatus for transferring objects comprising a robot blade attachable to a moveable member, the robot blade having an upper platform having a first object supporting surface and a lower platform having a second object supporting surface. Preferably the upper platform extends further than the lower platform such that the first object supporting surface is horizontally offset from the second object supporting surface. Also, the first object supporting surface and the second object supporting surface preferably occupy parallel planes.
Another aspect of the present invention provides transfer chamber having a robot blade comprising an upper platform having a first object supporting surface and a lower platform having a second object supporting surface, the robot blade attached to a rotatable and retractable robot within a transfer chamber of a processing system.
The present invention further provides a method for transferring objects comprising: providing a robot blade attachable to a moveable member, the robot blade having an upper platform having a first object supporting surface and a lower platform having a second object supporting surface; positioning the first object supporting surface to receive a first object; and positioning the second object supporting surface to deliver a second object. Preferably, the first object supporting surface is laterally offset from the second object supporting surface, and the first object supporting surface and the second object supporting surface preferably occupy parallel planes. The present invention provides a method of substrate transfer through a single insertion of the robot blade which reduces the amount of idle time that a chamber experiences during removal of a first substrate and insertion of a second substrate and simultaneously decreases the amount of time that a slit valve needs to be opened during this sequence by reducing the number of robot movements.
Another aspect of the present invention provides a multi-chamber process system, comprising: a transfer chamber; a plurality of process chambers connected to the transfer chamber; a robot within the transfer chamber; and a robot blade attached to the robot, the robot blade comprising an upper platform having a first object supporting surface and a lower platform having a second object supporting surface.
The present invention further provides a method of transferring objects through various chambers of a multi-chamber process system comprising: providing a transfer chamber connected to one or more process chambers; providing a robot within the transfer chamber; providing a robot blade attached to the robot, the robot blade comprising an upper platform having a first object supporting surface and a lower platform having a second object supporting surface; positioning the blade within a first chamber; retracting the blade out of the first chamber; positioning the blade within the second chamber; and retracting the blade out of the second chamber.
Another aspect of the present invention provides object transfers through a shuttle operation alternatively between the first object supporting surface and the second object supporting surfaces, which can be accomplished through a single insertion of the blade into a chamber. The shuttle operation reduces dead time and increases throughput while reducing the possibility of introducing contamination into the processing chamber.